1. Field of the Invention
The present invention relates to an analog quantity display method for displaying a measured analog quantity such as the size or shape of an object to be measured, an analog quantity measuring method for measuring the analog quantity, and a digital/analog display type measuring instrument for measuring an analog quantity such as the size or shape of an object to be measured.
2. Prior Art
As is well known, digital/analog display type measuring instruments such as dial gauges use a CRT display or a liquid crystal display to display a scale and a pointer as pictures or graphics in order to display results of measurements by analog display.
Since, however, analog display provided by such a CRT display or a liquid crystal display is actually in the form of digital display, its display resolution is limited. Therefore, it is generally difficult to display the scale and the pointer as pictures or graphics in detail, so that typical digital/analog display type measuring instruments require premeasurements using a gauge block.
Thus, the present assignee has proposed a digital/analog display type measuring instrument which allows both digital and analog measurements to be effectively executed even with omission of premeasurements using a gauge block, by Japanese Laid-Open Patent Publication (Kokai) No. 10-132546. That is, the proposed digital/analog display type measuring instrument has a large number of pointer segments arranged along a scale which indicate a measured value, and is characterized by including a switch which can independently switch an analog scale interval (weight per pointer segment), and a switch which can set a reference (zero) point for analog display at an arbitrary position of a probe.
However, the proposed digital/analog display type measuring instrument, which is used as a dial gauge or the like, displays the present measured value by lighting one of the large number of pointer segments arranged along the scale, thereby requiring the display to be relatively large in area. In addition, this instrument has a plurality of switches or the like for switching the analog scale interval and setting the reference point for analog display, resulting in a considerably large-sized display section.
Thus, the above conventional digital/analog display type measuring instrument has the disadvantage that if this measuring instrument is designed as a cylinder gauge for operation in a relatively small space, the display section of the gauge body has to be incomparably larger than the probe section. Therefore, this measuring instrument cannot be easily handled.
It is a first object of the present invention to provide an analog quantity display method and a digital/analog display type measuring instrument which require a relatively compact or small-sized display section and which is capable of constantly displaying, within an analog scale range, the present value, and upper and lower limit values of a set tolerance and peak values (minimum and maximum values), as well as the relationship between these values, without using switches for switching the analog scale interval and setting the reference point for analog display.
It is a second object of the present invention to provide an analog quantity measuring method which is capable of resuming a peak value hold function and automatically averaging a plurality of peak values to determine a measured value without any switch operation, thereby not only facilitating workpiece measurements and calibrations but also improving measuring reliability.
To attain the first object, according to a first aspect of the present invention, there is provided an analog quantity display method of counting displacement of a probe disposed in contact with an object to be measured, and analog-displaying a count value obtained by the counting, by an analog display section as an analog quantity, comprising the steps of displaying the count value by the analog display section as a bar graph comprising a large number of analog bars arranged in juxtaposition in one direction, and updating an offset provided for the analog-displayed count value in a manner such that a peak value of the count value is displayed within a possible analog-display range of the analog display section, if the peak value exceeds the possible analog-display range.
Preferably, the offset is updated in a manner such that the peak value is displayed at a substantially central position of the possible analog-display range of the analog display section.
Also preferably, the peak value is displayed by flickering at least one corresponding analog bar in the analog display section.
Also preferably, the peak value is displayed by changing display color of at least one corresponding analog bar in the analog display section.
Preferably, the analog quantity display method further includes the step of setting a measuring tolerance and setting the offset in a manner such that a numerical value of the set tolerance is displayed within the possible analog-display range of the analog display section.
More preferably, the step of setting the tolerance comprises setting a plurality of tolerance values as the tolerance and setting the offset and a display scale interval of the bar graph in a manner such that the plurality of tolerance values are displayed within the possible analog-display range of the analog display section.
In a preferred form, the step of setting the tolerance comprises setting a tolerance upper limit value and a tolerance lower limit value as the tolerance and setting the offset and a display scale interval of the bar graph in a manner such that the tolerance upper limit value and tolerance lower limit value are displayed symmetrically with respect to a central position of the possible analog-display range.
In a further preferred form, the step of setting the tolerance comprises setting the offset and the display scale interval of the bar graph in a manner such that the tolerance upper limit value and tolerance lower limit value are displayed symmetrically with respect to the central position of the possible analog-display range and such that a difference between the tolerance upper limit value and the tolerance lower limit value is substantially half the possible analog-display range.
Preferably, the numerical value of the set tolerance is displayed by reversing display state of at least one corresponding analog bar in the analog display section from a lighted state to an extinguished state or vice versa.
Also preferably, the numerical value of the set tolerance is displayed by changing display color of at least one corresponding analog bar in the analog display section.
Advantageously, the analog quantity display method is applied to a digital/analog display type measuring instrument comprising a counter for counting the displacement of the probe in contact with the measured object, a digital display section for digitally displaying the count value, and an analog display section located adjacent to the digital display section, for displaying the count value as the bar graph comprising the large number of analog bars arranged in juxtaposition in one direction.
To attain the second object, according to a second aspect of the present invention, there is provided an analog quantity measuring method comprising the steps of 1) counting displacement of a probe disposed in contact with an object to be measured, 2) comparing a count value obtained by the counting with a peak value of the count value and holding the count value as a new peak value depending upon a result of the comparison, and 3) executing the step 2) again if a difference between a present value of the peak value and a present value of the count value exceeds a predetermined value.
Preferably, the analog quantity measuring method further includes the step of repeatedly executing the step 2) whenever a new count value is obtained at the step 1) and holding and storing a plurality of peak values.
More preferably, the analog quantity measuring method further includes the step of averaging all the plurality of peak values stored to determine a measured value, in executing the step 2) in the step 3).
Advantageously, the analog quantity measuring method is applied to a digital/analog display type measuring instrument comprising a counter for counting the displacement of the probe in contact with the measured object, a digital display section for digitally displaying the count value, and an analog display section located adjacent to the digital display section, for displaying the count value as the bar graph comprising the large number of analog bars arranged in juxtaposition in one direction.
To attain the first object, according to a third aspect of the present invention, there is provided a digital/analog display type measuring instrument comprising a counter for counting displacement of a probe in contact with an object to be measured, a digital display section for digitally displaying a count value from the counter, an analog display section located adjacent to the digital display section, for displaying the count value as a bar graph comprising a large number of analog bars arranged in juxtaposition in one direction, and a control device for updating an offset provided for the analog-displayed count value in a manner such that a peak value of the count value is displayed within a possible analog-display range of the analog display section, if the peak value exceeds the possible analog-display range.
Typically, the digital/analog display type measuring instrument is a cylinder gauge for measuring bores of cylinders.
The above and other objects of the invention will become more apparent from the following drawings taken in conjunction with the accompanying drawings.